Strain assisted magnetoelectric coupling in ordered nanomagnets of CoFe2O4/SrRuO3/(Pb(Mg1/3Nb2/3)O3-PbTiO3) heterostructures

We have explored the electric field controlled magnetization in the nanodot CoFe2O4/SrRuO3/PMN-PT (CFO/SRO/PMN-PT) heterostructures. Ordered ferromagnetic CFO nanodots (similar to 300 nm lateral dimension) are developed on the PMN-PT substrate (ferroelectric as well as piezoelectric) using a nanostencil-mask pattering method during pulsed laser deposition. The nanostructures reveal electric field induced magnetization reversal in the single domain CFO nanodots through transfer of piezostrains from the piezoelectric PMN-PT substrate to the CFO. Further, electric field modulated spin structure of CFO nanomagnets is analyzed by using x-ray magnetic circular dichroism (XMCD). The XMCD analysis reveals cations (Fe3+/Co2+) redistribution on the octahedral and tetrahedral site in the electric field poled CFO nanodots, establishing the strain induced magneto-electric coupling effects. The CFO/SRO/PMN-PT nanodots structure demonstrate multilevel switching of ME coupling coefficient (alpha) by applying selective positive and negative electric fields in a non-volatile manner. The retention of two stable states of alpha is illustrated for similar to 10(6) seconds, which can be employed to store the digital data in non-volatile memory devices. Thus the voltage controlled magnetization in the nanodot structures leads a path towards the invention of energy efficient high-density memory devices.

Automated summary

This study explores the electric field controlled magnetization in nanodot structures. By applying electric fields, the magnetization reversal is achieved by transferring piezostrains to the ferromagnetic nanodots. The mechanism of electric field modulated spin structure is analyzed using x-ray magnetic circular dichroism. The nanodot structures can switch the coupling coefficient and maintain stable states for a long time, making them potential for non-volatile memory devices.